A petri dish kept in a lab has a colony of healthy bacteria. Every bacterium divides itself into two in exactly two minutes. Now the colony started with a single cell at 2 pm. If the petri dish was exactly half full of bacteria at 3 pm, when will the dish become full of bacteria?

Since every bacterium divides into two in two minutes and we know the fact that the dish was half filled with bacteria at 3 pm, after exactly 2 minutes, all will divide into two and will fill the petri dish. Thus, the petri dish will become full at 3:02 pm.

I am a book lover and i saw a book for Pound 97.
I am short of money , so i borrowed Pound 50 from my sister and 50 from my brother = Pound 100.
I bought the book, and had Pound 3 change. I gave brother Pound 1 and my sister Pound 1 and kept the other Pound 1 for myself. Now I owe my mum Pound 49 and my brother Pound 49. 49+49 = 98 + my Pound 1 = 99.

I borrowed my parents (Pound 50 + Pound 50 = Pound 100).
I bought the book for Pound 97 and i had Pound 3 change.
So, the money that i borrowed and bought the book are Pound 100 (borrowing money)
and the change Pound 3 also the borrowing money the book is Pound 97
Total: Pound 97 + Pound 3(the change) = Pound 100
The money that i used to buy the book all i borrowed.
Pound 97 is the borrowing money, change: Pound 3 also the borrowing money. Pound 97 + Pound 3 = Pound 100

A Japanese ship was making its way through the Arabian Sea. The captain felt like taking a bath and thus went to the bathroom after removing his Rolex watch and gold bracelet. When he returned back from the bathroom, he found out that his valuables were missing.

He suspected five of his crew members. He called them in and asked all of them what they were doing for the last 15 minutes. They replied as follows:parachute
The French cook (with a butcher knife): I was in fridge room getting meat for cooking.
The German Engineer (with some tools in hand): I was working on the generator engine.
The Bangladeshi seaman (empty handed): I was on the mast correcting the flag which was upside down by mistake.
The American Radio officer (with his headphones in hand): I was messaging to company that we will reach the port in the next two days that is Friday morning at 1100 hrs.
The Indian navigation officer (empty handed): I was taking a nap before my night watch began.

Upon hearing all of them, the captain found out who was the thief. How did he know that? Who is the thief?

A homicide detective is called at a crime scene. A man is lying dead in front of the building and seeking the position of the windows on the building and the position in which the body is lying, it is evident that the man jumped out from one of them and committed suicide.

The detective asks his team to collect the traces if they can find any on the body and heads towards the building. He goes to the first floor and towards the room that is on the front side. Inside the room, he lights a cigarette, walks towards the window facing the dead body, opens the window and throws out the cigarette. He then goes to the second floor and repeats the same process.

He keeps doing the same thing till he is done with all the floors and then takes the lift to the ground floor. Upon reaching there, he informs the team that it is not a suicide but a murder.

While the whole team is shocked to hear the revelation, he lights another cigarette and takes a hard puff.

Upon reaching each room, he found out that the window facing the dead body was closed. He had to open the window himself. This tells that there was somebody else with him who closed the window. If he would have committed suicide, at least one window would have been open.

A square island comprised of a square castle. A 14m wide trench surrounded the island from everywhere. Roman Empire wanted to invade the castle and gain the loot as well as possession of the island. They brought along wooden planks to cross the trench. However, they realized that the planks were just 13m long.

How did they use those planks to invade as well as capture the island ?

The three errors are as follows:
a) fynd is spelled wrong. The correct spelling is 'find'.
b) that is not appropriate to use here. It should be 'this'.
c) There are only two errors in the question and that is the third error because the questions asks us to find three.

In a guess game , five friends had to guess the exact numbers of balls in a box.
Friends guessed as 31 , 35, 39 , 49 , 37, but none of guess was right.The guesses were off by 1, 9, 5, 3, and 9 (in a random order).
Can you determine the number of balls in a box ?